[PATCH v4 03/59] do_fchownat(): import pathname only once

Al Viro
2026-01-08T07:36:48Z

Convert the user_path_at() call inside a retry loop into getname_flags() +
filename_lookup() + putname() and leave only filename_lookup() inside
the loop.

Since we have the default logics for use of LOOKUP_EMPTY (passed iff
AT_EMPTY_PATH is present in flags), just use getname_uflags() and
don't bother with setting LOOKUP_EMPTY in lookup_flags - getname_uflags()
will pass the right thing to getname_flags() and filename_lookup()
doesn't care about LOOKUP_EMPTY at all.

The things could be further simplified by use of cleanup.h stuff, but
let's not clutter the patch with that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/open.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index 82bfa06dbfa5..a2d775bec8c1 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -801,17 +801,17 @@ int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
int flag)
{
struct path path;
- int error = -EINVAL;
+ int error;
int lookup_flags;
+ struct filename *name;

if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
- goto out;
+ return -EINVAL;

lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
- if (flag & AT_EMPTY_PATH)
- lookup_flags |= LOOKUP_EMPTY;
+ name = getname_uflags(filename, flag);
retry:
- error = user_path_at(dfd, filename, lookup_flags, &path);
+ error = filename_lookup(dfd, name, lookup_flags, &path, NULL);
if (error)
goto out;
error = mnt_want_write(path.mnt);
@@ -826,6 +826,7 @@ int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
goto retry;
}
out:
+ putname(name);
return error;
}

--
2.47.3